US2469986A - Sound distributing system for drive-in theaters - Google Patents

Description

May 10, 1949. J. D. PHYFE SOUND DISTRIBUTING SYSTEM FOR DRIVE-IN THEATERS 2 Sheets-Sheet 1 if 5 y Filed March 5l, 1945 INVENTOR. JAMES D. PHYFE BY A TTORNEY J. D. PHYFE SOUND DISTRIBUTING SYSTEM FOR DRIVE-IN THEATERS 2 Sheets-Sheet 2 May 10, 1949.

Filed March 31, 1945 INVENTOR. .JA/v5.5 D. PHy/-E ATro/a/viy Patented May 1.0,Y 1949 SOUND DISTRIBUTING SYSTEM FOR DRIVE-IN THEATERS .ia-:nes D. Phyfe, Indianapolis, Ind., assignor to Radio Corporation of America, a corporation of Delaware Application March 31, 1945, Serial No. 585,830

13 Claims.

This invention relates to sound distributing systems, and more particularly to a system of loudspeakers for distributing sound in arenas, amphitheaters, and the like, such as the so-called open air drive-in theaters.

Theaters of this type for the exhibition of motion pictures generally comprise a series of arcuate ramps divided into parking stallways arranged to face an elevated screen at a central point which may be the focal point of the ramps The ramps are so inclined with respect to `the screen that, when automobiles are parked thereon, the occupants thereof can view the screen through the windshields. Such a theater is shown, for example, in U. S. Patent No. 1,909,537 granted to R. M. Hollingshead, Jr.

For the exhibition of talking motion pictures, a sound distributing system is, ofcourse, necessary to go with the action portrayed on the screen. Various forms of loudspeaker arrangements have been suggested heretofore, among which is an arrangement of loudspeakers behind the screen; mounting individual speakers at each stallway to face the radiators of cars parked therein; `and mounting portable loudspeakers between stallways so that the patrons can lift the loudspeakers into the cars. Of the systems heretofore proposed, the latter was round most advantageous in certain respects. However, as arranged heretofore, the latter system has several serious disadvantages, the chief one of which is that ii any one of the loudspeaker cables were short circuited, either the particular ramp in which it is installed or the entire system would go dead, or else a serious loss of volume would result on account of the adverse loading effect on the amplifier output.

The primary object of my invention is to provide an improved sound distributing system for air theaters and the like which will not be subject to the aforementioned and other disadvantages characteristic of prior art systems.

More particularly, it is an object of my present invention to provide an improved mounting and circuit arrangement for so called in-car loudspeakers, that is, loudspeakers which may be taken into the automobiles by the occupants.

Another object of my present invention is to provide an improved method of mounting and connecting in-car speakers to ramp wiring in drive-in theaters.

Still another object of my present invention is to provide an improved mounting for in-car speakers such that the speakers may be more easily reached by the patrons without having to leave their automobiles.

A further object of my present invention is to provide an improved sound distributing system ior drive-in theaters in which the short circuiting or any one loudspeaker will have no adverse eiiect on the remainder of the system but will aiect only the particular channel in which the short-circuited loudspeaker is connected.

Still a iur-ther object of my present invention is to provide an improved sound distributing system as aforesaid which can be serviced very easily either for repairs, when necessary, or for winter conditioning.

Another object of my present invention is to provide a sound distributing system as above set forth in which the loudspeakers for the respective ramps are arranged in channels designed to feed two adjacent stallways and in which any one or more channels may be isolated or by passed, should a short circuit develop between any two t channels, Without affecting the operability of the remaining channels.

Still another object of my invention is to provide an improved sound distributing system as above set forth in which the necessity for under- 3 ground splices or connections is obviated, thereby resulting in a safety factor not found in prior art installations.

lt is also an object of my present invention to provide an improved sound distributing system for open air theaters, arenas, or the like which less expensive to install and operate than comparable prior art systems, and which is highly efoient in use.

In accordance with my present invention, I arrange throughout the entire area of the theater and at alternate boundaries between adjacent stalls in the various rows or parking ramps suitable supporting standards on each oi which is mounted a junction box. This junction box carries on opposite ends or sides thereof facing the two stallways on either side thereof suitable receptacles in each of which is removably mounted a portable loudspeaker. Each junction box is so dimensioned relative to the adjacent stallways that the occupant of an automobile parked therecan reach the loudspeaker merely by reaching out oi the window and without the necessity of getting out of the automobile. Preferably, the supporting standards are mounted on sloping, concrete bases so arranged that, should the driver approach close to the adjacent loudspeaker when parking his car, the adjacent wheel will strike the base before the body of the car would strike the speaker, so that damage to the speaker from this cause is avoided.

The loudspeaker receptacles are so disposed on the junction boxes and the loudspeakers are so mounted thereon that the loudspeakers are arranged in an upright position, This makes it easier to reach and handle the loudspeakers. Moreover, such a mounting also permits the patron to enjoy the performance without bringing the loudspeaker into the car if he so desires. A volume control on the front panel of the loudspeaker casing enables the patron to readily adjust the volume to suit his taste whether the loudspeaker remains in its receptacle or is brought into the car.

Within the junction boxes are mounted a suitable terminal board and loudspeaker coupling transformer through which both loudspeakers of any one junction box may be connected to suitable feeder cables. Heretcfore, so far as I am aware, similar installations have utilized an individual transformer for each loudspeaker. Thus, if a pin or other metallic object is pushed into the cable, as is occasionally done by pranksters to short circuit a loudspeaker, the entire system either goes dead or is considerably reduced in volume with accompanying distortion resulting. In accordance with my invention, by connecting the loudspeakers in groups of two to the secondary winding of a transformer housed in the junction box, thn short circuiting of a cable leading to one of an associated pair of loudspeakers would merely reflect a short circuit at the secondary circuit of that particular transformer. The primary winding circuit according to my invention preferably has an isolating resistor in series therewith, and the irnpedance of the primary circuit is very high conipared with the impedance of the secondary circuit. Thus, an undesired change in the secondary circuit such as results from short circuiting the same will have substantially no adverse effect upon the related primary circuit, and therefore the remainder of the sound distributing system will not be disturbed. Furthermore, by using only one transformer to each pair of loudspeakers, the number of transformers required is reduced by one half.

Another advantage of my improved system is that the parts within the junction box may be readily reached for servicing, when necessary, by merely removing the cover of the junction box. Also, the entire junction box may be held place on the supporting standard by screws or bolts which, upon removal, will permit removal of the junction box and the two loudspeakers carried thereby as a unit. Thus, these units can be quickly removed and stored away for the winter. Suitable caps may then be placed on the standards to protect the feeder cables therein from attack by the elements during the winter season.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description of one ernbodiment thereof, when read in connection with the accompanyingr drawings in which Figure 1 is a fragmentary, perspective view of an outdoor theater provided with a sound distributing system according to my present invention,

Figure 2 is an enlarged, detailed view showing a supporting standard with its junction box, and

showing also the manner in which a loudspeaker may be supported on the junction box or mounted in an automobile,

Figure 3 is an enlarged, sectional View taken on the line lll-lli of Figure 2,

Figure i is a wiring diagram of one circiut according to my present invention,

Figure 5 is a front elevation of one form of loudspeaker according to my present invention, and

Figure 6 is a fragmentary, detailed View of the upper end of a supporting standard with a cover or cap applied thereto in place of the junction box-of Figure 2.

Referring more particularly to the drawings, wherein similar reference characters designate corresponding parts throughout, there is shown, in Figure l, an outdoor theater provided with a plurality of parking ramps i each divided into a plurality of adjacent stallways 3 by suitable boundaries, such as the markers il. The ramps l may be inclined upwardly toward a screen 'I so that occupa-nts in automobiles s parked in the stallways 3 will have a clear view of the screen through their respective windshields. Moving pictures or the like are projected onto the screen l from a projection booth l i in well known manner.

For the purpose of distributing uniformly throughout the entire theater sound related to the action portrayed on the screen, l provide at alternate boundaries 5 suitable mountings I3, each for a pair of loudspeakers in association with the adjacent two stallways. Each mounting E3 comprises a concrete or other suitable base i5 from which rises a tubular supporting standard il having a plate is removably secured to a flange llo at the upper e d thereof, as by screws 2l. A cover which is removably secured to the plate l@ by screws or the like 25 constitutes, lwith the plate i9. a junction box within which are housed a coupling transformer 2l and a terminal block or strip 29.

Secured to the junction box cover Z3 at the oppcsite ends thereof alongside the adjacent stallways are a pair of wire baskets or other suitable receptacles 3i each of which removably receives a loudspeaker S3. The loudspeakers are preferably of the electrodynamic type and include a volume control on the front panel of the casing thereof. Each loudspeaker casing is also provided with a mounting bracket 3l by means of which the loudspeaker may be mounted on the window frame of an automobile with the loudspeaker inside the car, as shown to the right of Figure 2. llhe junction box l, Z3 is of such a length that it extends into fairly close proximity with the automobiles properly parked the adjacent stallways, so that the occupants of the cars can easily reach the loudspeakers by merely extending the arms out of the windows, thus avoiding the necessity of getting out of the cars. Similarly, the loudspeakers may be replaced in their receptacles si from within the car through the open window thereof and without getting out of the car.

Each loudspeaker lil has its voice coil 33a connected to the secondary winding Zia of the associated transformer through the volume control 35 and an elongated flexible cable Iig, the two loudspeakers of any associated pair being connected in parallel relation to each other across the transformer secondary winding, as seen in Figure 4. The primary winding 2lb of each transformer is connected through a feeder cable 4l, which extends through the associated tubular standard l1, to a main cable or transmission line 43 which is connected through a suitable amplifier 45 to a source of electrical signals 41 corresponding to the sound to be distributed and constituting a sound source. The sound source may be derived from the conventional sound track on the moving picture nlm or, in the case of a public address system or the like, it may be a microphone or similar device. Connections between the transformer 27, the cables 39 and the cable 4| are made, in each case, through the associated terminal board 29, as shown in Figure 3.

It will be apparent, from the foregoing description, that the main cable or transmission line 43, which is under ground, the cables il which are within the tubular standards il and the transformers 27 with connections thereto which are in the junction box I9, 23 are tamperproof for practical purposes, A prankster seek-I ing to upset the sound distributing system by pushing a pin through one of the cables @il can only succeed in short circuiting the secondary winding circuit of the associated transformer therefore will render inoperative only the two loudspeakers connected thereto. The secondaryT circuit, even when both loudspeakers connected thereto are operative, has a very low impedance (for example, approximately 2 to 4 ohms). The primary circuit, on the other hand, has a very high impedance (for example, from 5,000 tc 10,()60 ohms over the frequency range of in terest). The primary winding impedance may be made high in any suitable way, as by provid ing a primary winding which has a relatively high D. C. resistance. In any case, by making' the impedance of the primary circuit high compared to that of the secondary circuit, and short circuiting or other undesired eifect pron duced in the secondary circuit will have substan tially no adverse eiect in the primary circuit. Consequently, the main cable d3, across which all of the cables ll and their associated channels are connected in parallel relation, will not become short circuited and therefore the remainder of the system will remain operative. if desired, isolating resistor 9 may 4be connected in series with the primary winding 2lb to provide the requisite impedance in the primary circuit. ihm serting such an isolating resistor in the primary circuit has the advantage that, even if the plimary winding 2lb itself develops a short circuit, the series resistor 49 will prevent a short circuit to the ramp wiring. The resistor iid is of auch value in each case that only a slight loss of power will be effected when it is in circuit, but its value is large enough so that patrons utilizing the loudspeakers of any other of the channels will be iin-- aware of a short circuit in any particular loudn speaker or coupling transformer.

From the foregoing description, it will be apparent to those skilled in the art that have provided an improved sound distributing system for outdoor theaters and the like which has the advantages pointed out heretofore. Each channel, according. to the present invention, is made independent of any other channel, and since only one transicrmer is needed for each pair of loudspeakers, the cost of the installation is reduced considerably. It will also be apparent that the system is, generally, more tamperproof than prior art systems, thereby insuring a longer life therefor. The fact that the cover 23 of the junction box `can be removed easily merely by removing the lia to cove-r the cable 4l and prevent rain, snow,

dust or any other foreign matter from entering the standard il and damaging the cable therein. Although l have shown and described only a single embodiment of my invention, it will undoubtedly be apparent to those skilled in the art that many other variations thereof are possible. 'i' therefore desire that my invention shall not be ued except insofar as is made necessary by the prior art and by the spirit of the appended claims.

as my invention:

in an outdoor theater having a screen and area adjacent thereto comprising a plurality of automobile stallways in which automobiles may be parked facing said screen, a sound distributing system for simultaneously conveying to occupants of said automobiles at pairs of adjacent stallways sound related to action portrayed cn said screen which comprises, in combination with a source oi electric signals representing said sound a supporting member located between the stal ways constituting each of said pairs through- 2; said area, a pair of loudspeakers loosely carried by each of said supporting members for ready therefrom each into a separate stallway and an automobile in said stallway, and circuit means carried by said supporting members couig said loudspeakers to said source.

in an outdoor theater having a screen and an adjacent thereto comprising a plurality of automobile stallways in which automobiles may be parked facing said screen, a sound distributing system for simultaneously conveying to cc ants ci said automobiles at pairs of ad- "it stallways sound related to action poron said screen which comprises, in conibin tion with a source of electric signals repreng said sound, a supporting member located b weon the stallways constituting each of said s throughout said area, a pair of loudspeakers ted on each of said supporting members one on each side thereof in association with an acent stallway, said loudspeakers being each loosely carried by said supporting members for reni-oval therefrom into an adjacent stall- Way and an automobile therein, and circuit iii."

i that circuit means includes a cable .n carried by each of said supporting and flexible cables connecting each of e arwcioted loudspeakers to said cable conrl nexible cables each being of a length nt tc permit said loudspeakers to be disroln said supporting member to the inrs of the automobiles in their respectively lated stallways.

fl. In an outdoor theater having a screen and a plurality of adjacent automobile stallways in which automobiles may be parked facing said screen, a sound distributing system for conveying to Aoccupants of said automobiles sound related to action portrayed on said screen which comprises, in combination with a source of electric signals representing said sound, a plurality ci supporting members distributed throughout the area occupied by said stallways and located at alternate boundaries between said adjacent stallways one at each of said alternate boundaries, a pair of loudspeakers mounted on each of said supporting members, each of said loudspeakers being associated with a separate one of the two stallways on each side of their respective supporting members and being loosely carried by their respective supporting members for ready removal therefrom into the automobiles of their respectively associated stallways, and circuit means coupling all of said loudspeakers to said source.

5. The invention set forth in claim a characterized in that each of said supporting members includes a junction box housing certain elements of said circuit means, and characterized further in that said circuit means also includes a plurality of ilexible cables, one for each of said loudspeakers, connecting said loudspeakers to said certain elements of their respectively associated junction boxes.

6, The invention set forth in claim l characterized in that each of supporting members includes a junction box, cl'iaracterized further in that said circuit means inclu-:les (l) a transformer housed in each of said junction boxes and (2) ineens coupling the primary winding oi each of said transformers to said signal source, and characterized still further in that said circuit means also includes a, plurality ci iiexible cables, one for ach of said loudspeakers, connecting each of said loudspeakers to the secondary winding of the transformer in its associated junction box.

7. The invention set forth in claim i c7 aracterized in that each of said suppoi c, embers includes a, junction box, characterized further in that said circuit means includes (i) a er housed in each of said junction boxes and (2) means coupling the primary Winding of each of said transformers to said signal source, and characterized still further in that said circuit means also includes a plurality of flexible cables, one for each of said loudspeakers, connecting each of said loudspeakers to the secondary wi or' transl` rmer in associated juliet said loudspeakers being normally mounted on their respectively associated junction bones, and said flexible cables being each oi a length sunlcient to permit displacement of their respectively connected loudspeakers from their associated junction boxes to the interior of the automobiles in their respectively associated stallways.

8. The invention set iorth in claiii e characterized in that each of said supporting members includes a junction box, characterized further in that said circuit means includes (i) a transformer housed in each of said junction boxes and (2) means including an isolating resistor in series with the primary winding of each oi said transformers coupling the respective primary windings torsaid signal source, and cl'iaracteriaed still further in that said circuit means also includes a plurality of rlexible cables, one for each 0i said loudspeakers, connecting each of said loudspeakers to the secondary winding of the transformer in its associated junction box.

9. In a sound distributing system, the coinbination with a source of electrical signals representing the sound tol be distributed and comprising a transmission line oi a plurality of distribution channels connected in parallel relation to each other across the output of said source along said transmission line, each of said channels comprising an electrical network which includes (l) a transformer having a primary winding connec-ted across the output of said source through said transmission line and a secondary winding, (2) a plurality of loudspeakers connected in paraliel relation across said secondary winding, the circuit of primary winding having an impedance which is high compared to the impedance of the circuit of said secondary winding, whereby an undesired change in impedance of said secondary winding circuit will have substantially no adverse effect upon the impedance of said transmission line, and (3) an isolating resistor in series with said primary winding, said isolating resistor having a value of resistance such that it further `imparts to said primary winding circuit a relatively high impedance compared to the impedance ci said secondary winding circuit.

l0. In a sound distributing system, the combination with a source of electrical signals representing the sound to be distributed and comprising a transmission line, of a plurality oi distribution channels connected in parallel rela-- tion to each other across the output of said source along said transmission line, each of said channels comprising an electrical network which includes a transformer having a primary winding connected across the output of said source through said transmission line and a secondary winding, a plurality of loudspeakers connected in parallel relation across said secondary Winding, the circuit oi said primary winding having an impedance which is high compared to the impedance oi the circuit of said secondary winding, whereby an undesired change in impedance of said. secondary winding circuit will have substantially no adverse effect upon the impedance of transmission line, a plurality of supporting members, one for each of said channels, and a housing carried by each of said supporting members, the transformer of each of said channels being contained within its associated housing, and the loudspeakers ci each channel being removably mounted on the junction box of their associated channel for ready removal to remote points while still remaining connected to the secondary winding of their associated transformer.

ll. In a sound distributing system, the combination oi a tubular supporting standard, a housing mounted on said standard and having communication with the bore thereof, a receptacle secured to said housing, a loudspeaker removably carried in said receptacle, and circuit means coupled to said loudspeaker for connecting said loudspeaker to a source of signal energy, said circuit means including a transiormer within said housing, a iirst cable extending through said standard and connected to the primary winding of said transformer, and a second, flexible cable extending into said housing and connecting said loudspeaker to the secondary winding of said transformer, said second cable being of suicient length to permit removal of said loudspeaker from said receptacle to a remote point While said loudspeaker remains connected thereby to said secondary Winding.

12. The invention set forth in claim l1 characterized in that said housing is removably associated with said standard, and characterized further by the addition of a cap member adapted to serve as a cover for said standard upon removal of said housing therefrom whereby to protect said iirst cable from attack by the elements when said housing is removed from said standard.

13. In a soun-d distributing system, the combination of a base, a tubular supporting standard rising therefrom, a housing constituting a junction box mounted on said standard and having communication with the bore thereof, a pair of receptacles mounted on opposite sides of said housing, a pair of loudspeakers one of which is removably carried in one of said receptacles and the other of which is removably carried in the other of said receptacles, land circuit means coupled'to each of said loudspeakers for connecting said loudspeakers to a source of signal energy, said circuit means including a transformer within said housing, a rst cable extending through said standard and connected to the primary winding of said transformer, and a pair of additional, flexible cables each connected to a separate one of said loudspeakers, said additional cables extending into said housing and connecting said loudspeakers in parallel relation across the secondary winding of said transformer, and said additional cables being each of sufficient length to permit removal of their respective loudspeakers into the interiors of automobiles parked alongside of said junction box on either side thereof while said loudspeakers remain connected thereby to said secondary winding.

JAMES D. PHYFE.

REFERENCES CITED The following references are of record in the le of this patent:

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